The present invention relates generally to remote control of unmanned aerial vehicles. More particularly the invention relates to a method according to the preamble of claim 1, a computer program according to claim 13, a computer readable medium according to claim 14 and an unmanned aerial vehicle according to the preamble of claim 15.
Remotely controlled unmanned aerial vehicles (UAV:s) represent an increasingly important field of aircraft technology, particularly for the military sector. UAV:s may namely be used to perform a large variety of military operations, such as reconnaissance flight and target combating. Therefore, the prior art includes various examples of solutions for controlling a UAV. For instance, the U.S. Pat. No. 6,377,875 describes a method for controlling a UAV wherein upon loss of radio contact between a control station and the UAV, the UAV flies according to a pre-programmed safety route. During any interruption of the radio contact, the UAV will fly on a substitute route, which is calculated in the UAV. Various methods of returning the UAV after a completed mission, or at the event of loss of radio contact, are also described.
However, the problem of preventing a UAV from crashing uncontrollably during a time period when the radio contact is broken remains to be solved. Namely, basically at any time, a critical fault condition may arise in the UAV, which renders all return routes from the vehicle's present location impossible, and instead forces the UAV to perform a relatively speedy landing operation. Naturally, if such a landing takes place without particular measures being taken, there is a substantial risk that serious adverse effects occur on the ground, for example in the form of injuries to personnel or material damages. In fact, no solution is yet known which is capable of handling a critical fault condition in a UAV concerning its flight control parameters without a command link between the UAV and a control station being active.